In a court of law, it is essential to establish the identity of everyone involved in the case, as well as their connection to the case. This can be done easily by using markers.
What is a marker?
A marker is a specific field which may vary from person to person. Some markers, such as gender markers, can only indicate 2 options, or 3 options (M, F, X) if you are in Australia, to allow for persons who are born intersexed. Other fields, such as name markers or fingerprints, have effectively infinite options.
Some marker fields only show up after they are activated by specific events. For example, marker fields on a credit report are created every time you open a credit-related account, and a marker is made if you miss a payment or use a high percentage of your available credit.
= Biological markers =
With the exception of identical twins, everyone has unique DNA within the acceptable bounds of probability. Forensic DNA testing identifies markers in a few parts of that DNA which are likely to have individual variation.
Other forms of biological markers include fingerprints and blood markers. There are many different blood markers, such as the familiar A/B/AB/O blood groups and Rh factors.
Identifying a person in a court of law
Markers can be used for identification in a court of law in several different ways. Basic markers will be adequate in most cases, depending on the case and region.
In general, all that is needed is the person’s legal name, along with a government-issued piece of photo identification to establish identity. A signature, place of residence, or confirmation of citizenship or legal residency may also be required. However, bear in mind that the person who holds title or lease for the place of residency may not be the person who lives there.
These markers will work in many cases without any more detail needed. Name and gender markers are universal. However, they are not perfect.
Name markers are subject to duplication. Some names are much more commonly used than others. The most common names will always identify more than a single person, but even less common names may be duplicated.
Name markers are also not permanent. Names commonly change at marriage, and may also change at other points in life.
Even the gender marker is no longer considered permanent. The gender marker for transgender people may not be consistent among all their identification, and their looks may not match the gender marker.
Where simple identification has been compromised, other types of markers can be used to establish continuity of the person. Where the compromise was without criminal intent, continuity can usually be established with a residence record and a credit report.
= Fingerprints, blood markers, and DNA =
Fingerprints are usually used only in crinimal cases. DNA and blood markers are used in paternity suits as well as criminal cases. Like DNA, fingerprints are unique outside identical twins, but blood markers are not.
Assuming that proper procedure has been followed throughout, all these methods may be useful and are admissible as evidence of identity in a court of law. They may be used as evidence for a person’s identity relative to the case. They may also be used to exonerate a person.
In general, blood markers should only be used for broad exclusion. They can also be used to indicate that further examination should be done. A rare blood group is not proof of identity, but can be strong evidence of it.
DNA markers are not a perfect way to connect a person with the case. This is because the DNA as a whole is unique, but the sites examined for variation are not. In many cases, the frequency of the pattern in the population as a whole is not yet known.
However, for the same reason, DNA markers are a very good way to exonerate a person. If the DNA markers match, there is still a chance that someone else may have the same match. If they don’t, then that DNA sample could not possibly have come from that person.
Finally, people with adermatoglyphia don’t have fingerprints. This genetic abnormality in SMARCAD1 can affect entire families, so it may serve as an identity marker in its own right. The same condition also affects footprints. It is still unknown whether the same mutation is responsible for every person who lacks fingerprints.